Mods for robotic VX

[Art]

Austin Robot Technology has selected a VX as the off-road vehicle to serve as a platform for our robotic entry into the 2005 DARPA Grand Challenge. I would like to use this thread to get advice from members of this club regarding off-road matters. The race consists of 175 miles across the desert Southwest, most likely the Mojave Desert. Last DARPA Grand Challenge was held for the first time last year, the course was 142 miles from Barstow California to Primm Nevada. Most of the course consisted of unpaved rocky service roads along power lines. Some of the route went over paved roads (less than 20%). Speed is moderate (20 to 30 MPH). We will have some means of isolating the computers from shock, dust, and heat.

Let me start by asking about tires. We are considering 265-75-R16 BFG A/T KO.
An alternative is Firestone Destination M/T 265-75-R16. We want puncture resistance, we want traction. We have a conflicting desire for a "soft" ride.

Any advice on tires, comments about the above choices or other suggested tires. Any advice on tire pressure?

Thanks for any help!

Art

[Cyrk]

Cannot offer any advice, but TOO COOL, lets see some pics, videos... whatever. Good Luck!

[Tone]

Welcome and good luck! Bob Land Racing did Laughlin and a number of other notable offroad events - not sure if his site is still around but you may wish to search the web or this site. Cyrk, you have the autographed picture with stats on it - see what he lists for tires.

I'd think you'd most importantly want to use tires that competitors had used in Baja or Dakar or any of the other big events.

[AlaskaVX]

I'm not positive on what the conditions of the desert are but if it's deep sand the Mickey Thompson Baja belted tires did well here. I would not do a standard MT style tire (Like BFG MT) in the sand as it will dig in too much. You would want the widest tires possible too to keep you floating on top of the sand. For me the 31x11.5 Mickey T. Baja belted did very well in glacier silt and deep sand. No lift required just a little bit of trimming up front of the front wheel wells. The Baja Claws mounted backwards might do real well too.

But if a MT tire will work I can't believe how well my TrXus MT's do in all the conditions I have put them through. Not sure if they make ones that will fit, but most likely they do.

All the above tires give a descent ride.

[Nazrat]

Personally, I'd find a hard-ish compound all-terrain (AT) tire, or get some kind of run-flat insert to put in an AT tire. (maybe have new centers welded into H1 runflat rims) There's obviously no way to change a flat out there. If I was running normal AT tires at 20-30mph I'm not sure that I'd want less than 20psi, probably around 25-30psi. You risk popping them the higher the PSI, but you risk rolling it off of the bead at lower pressures.

I have a few pics of Bob Land's VX, and the tires that he used. They were not off-the-shelf tires. Bob told us that he had them custom cut, and were a very hard rubber compound. The ones on the VX in the pics below have a race on them, and I had a hard time telling them from the brand new ones in his shop.

http://tad.grosvenor.org/gallery/MoabMay2001/a22_19A

You can see the size here: (7.50 R 16 it looks like to me)
http://tad.grosvenor.org/gallery/MoabMay2001/a24_21A

Here's the tread that he ran on his Amigo:
http://tad.grosvenor.org/gallery/MoabMay2001/a21_18A

Keep us up to date. This company has an entry as well:
http://www.mitre.org/news/digest/adv...hallenge1.html

A group from Florida entered a 1993 Trooper last year.
http://cimar.mae.ufl.edu/teamcimar/g...2004/index.htm

-Tad

[Moncha]

I saw this and the other post inthe intro forum.. First, WELCOME!! The project sounds very cool. I even watched the last one when it was presented to TechTV.
If you would like, I can made a specific forum to keep all of your updates and questions in one place so it doesn't get spread out. Let me know.

[Art]

If you would like, I can made a specific forum to keep all of your updates and questions in one place so it doesn't get spread out. Let me know.

That sounds like a good idea. Thank you!

[Moncha]

There ya go!

[nocturnalVX]

I run Pro Comp ATs on my VX and they are very good tires. Pro Comp also has a mud-terrain and an "X-terrain" if you want a more aggressive tread pattern. Here's a link to their website... http://www.procomptires.com/ . Good luck!

[SGT.BATGUANO]

We need to get a BIG vehicross.info sticker on this robo-vx.

Are sponsorships available and how much does sign space go for?

[Moncha]

My thoughts also, was just giving them time to settle in

[Art]

My thoughts also, was just giving them time to settle in

We consider this forum an invaluable resource... we'll put the sticker for free. Where do you want it? Do you have encapsulated postscript (.EPS) file with the artwork? We'll have it made at FastSigns. Thanks!

Art

[Moncha]

Very COOL!!!
As it happens, I do have an .eps file also .psd and anything else you may need. The .psd and .eps banner I have is 24" long but can be resized and is 300dpi. I have smaller if you want also.. Tell me where it needs to be sent and I can get it there right away.

"Where do you want it?" - On the windshield of course But, I don't want to get pushy.

[Swordy]

I spend quite a bit of time playing in the California Desert. In fact I'll be heading out there for the weekend in a few hours. I'll vote for Dirtgripz or a similar tire. 11.5 to 12.5 wide. Use as tall a tire as you can reasonably fit without interference. Something with extra thick (E rated) sidewalls to deal with the jagged rocks. Air them down to like 13-15 lbs. for good stable contact, shock absorbtion, and floatation. For good bite, they should be luggy critters with a decent amount of void between the lugs. The sidewalls should be fairly tall.
If you go with a thinner C or D sidewalled tires, to obtain the desired squish factor, air up to a higher pressure. Obtaining the right amount of air-down is important to keep you from sliding on hard surfaced rock laden corners. They do need to be stiff enough to minimize body roll though. Use some strong cast smaller diameter rims. Not steel. Use some fairly stiff shocks in the rear, or/and split your rear bumpstops since riding on the bumpstops kills your traction at any appreciable speed.
At the risk of sounding conceited or arrogant... Actually,, to haul @ss across the Ca desert. I'd pretty much set it up like mine.

[mbeach]

I'm assuming that this project is on some sort of budget.

I'd pick something not horribly expensive -your money would be better spent in software rather than tires. Having spent a fair bit of time driving about the Mojave Desert, I'd have to echo AlaskaVX's comment about flotation -fatter the better. The MT Bajas are reasonably priced, and offer excellent sand traction. Your speed(s) and route will not likely take you across tire-puncturing terrain, so just steer clear of any brush and mountains and your tires should be fine. You can add a can of Fix-A-Flat to each one to give you piece of mind.

Your robot's biggest enemies will be heat and vibration. Heat can be beat with a fair amount of A/C, but the VX is a well-known rump-shaker. Since plush suspensions aren't my thing, I'll have to hand that one off.